What can one do with a Raspberry Pi?

The Raspberry Pi is a very compact and minimalistic computer that costs around $25—$35 and is about the size of a credit card. It runs a version of Debian Linux and has support for Python.

I am thinking about buying one (it is a charity), and I am wondering what exactly I should do with it. It seems to be the perfect platform for some sort of programming/building project, given it’s small size. Do you have any ideas for projects that I could do with a Raspberry Pi?